3: If required, You can change default region by clicking the region menu on upper-right corner.

4: On left side panel click on "Instances" menu, then click on "Launch DB Instance" button.

5: Now you must be on "Select Engine" page, The most important thing here is "Only enable options eligible for RDS Free Usage Tier" option you can see at bottom of this page. Click on that checkbox if not already selected, so that options that are not covered under the Free Tier will be inactive.

Note: Please make sure, do not cross RDS Free Tier limit otherwise it will charge you accordingly in Free tier as well.